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What are the Characteristics of amorphous solids ?

Posted by Ankur Majumdar (Apr 23, 2017 8:56 a.m.) (Question ID: 5003)

  • Answers:
  • AMORPHOUS SOLIDS :-

    • It has irregular shape
    • isotropic in nature
    • has short range order
    • they are pseudo solids or super-cooled liquids
    • When cut with a specific sharp edge tool, they cut into two pieces with irregular surfaces 
    Answered by Aashka Shah (Apr 23, 2017 11:54 a.m.)
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Silver has atomic radius of 144pm and density of silver is 10.6 g cm3. To which type of cubic crystal silver belongs? 

Posted by Hritika Jain (Apr 21, 2017 10:44 a.m.) (Question ID: 4978)

  • Answers:
  • But the question is this much only and is from vibrant academy

    Answered by Hritika Jain (Apr 25, 2017 10:08 a.m.)
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  • Sorry but your question lacks the content to give exact answer. 

    Answered by Payal Singh (Apr 21, 2017 2:27 p.m.)
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But if we look like Fe<font size="2">2+ </font>as Cr and

Fe<font size="2">3+</font> as V

in that sense then Fe<font size="2">2+</font> should be the correct,,,,

is my method correct?????

My actual doubt was 

which is having maximum number of unpaired electron

Fe<font size="2">2+</font> or Fe<font size="2">3+                      </font>

Posted by Aashka Shah (Apr 19, 2017 9:52 p.m.) (Question ID: 4954)

  • Answers:
  • No ur method is not correct. Because electrons removed from outermost shell that is 4s in case of Fe.

    Answered by Payal Singh (Apr 20, 2017 3 p.m.)
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which is having maximum number of unpaired electron

Fe2+   or   Fe3+

Posted by Aashka Shah (Apr 19, 2017 1:33 p.m.) (Question ID: 4946)

  • Answers:
  • But if we look like Fe2+  as Cr  and

    Fe3+ as V

    in that sense then Fe2+ should be the correct,,,,

    is my method correct?????

    Answered by Aashka Shah (Apr 19, 2017 5:13 p.m.)
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  • Electronic Configuration of

    Fe = {tex}1s^2 2s^2 2p^6 3s^2 3p^6 3d^6 4s^2{/tex}

    Electronic Configuration of

    Fe2+  = {tex}1s^2 2s^2 2p^6 3s^2 3p^6 3d^6 {/tex}

    Electronic Configuration of

    Fe3+ = {tex}1s^2 2s^2 2p^6 3s^2 3p^6 3d^5{/tex}

    So Fe3+ has more unpaired electron. 

    Answered by Payal Singh (Apr 19, 2017 4:38 p.m.)
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Can anyone give me any trick to remember d & f block elements easily

pl. reply fast its urgent 

 

Posted by Aashka Shah (Apr 18, 2017 7:41 p.m.) (Question ID: 4939)

  • one conformation not elements but the whole chapter with highlights or anything if someone could help me with it

    Posted by Aashka Shah (Apr 18, 2017 7:42 p.m.)
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How to convert galvanic cell into electrolytic cell? 

Posted by Pallavi Kapoor (Apr 18, 2017 6:27 p.m.) (Question ID: 4937)

Write explanation of galvanic cell? 

Posted by Pallavi Kapoor (Apr 18, 2017 6:26 p.m.) (Question ID: 4936)

What is the difference between amorphous and crystalline solids on the basis of cleavage?

Posted by Ankur Raj Singh (Apr 15, 2017 8:45 p.m.) (Question ID: 4892)

  • Answers:
  • Amorphous solids don't break at fixed cleavage planes whereas Crystalline solids cleavage along particular direction at fixed cleavage planes.

    Answered by Payal Singh (Apr 17, 2017 6:39 a.m.)
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What is kernals

Posted by Dev Lavania (Apr 13, 2017 3:53 p.m.) (Question ID: 4865)

  • Answers:
  • Kernels are basically the atom without its valence shell .all the inner shells and the nucleus make up the kernel. The valence shell is represented outside the kernel.

    Answered by Payal Singh (Apr 17, 2017 6:54 a.m.)
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What product is formed when 1-bromo-2-chlorocyclobutane combines with sodium /ether 

Posted by Swastika Chandan (Apr 12, 2017 5:34 p.m.) (Question ID: 4860)

  • Answers:
  • This is example of Wurtz Reaction . Product ll be Bicyclobutane.

    Answered by Payal Singh (Apr 17, 2017 5:51 p.m.)
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Why enthalpy of mixing and volume of mixing of the pure components to form the solution is zero?

Posted by Pallavi Kapoor (Apr 11, 2017 9:12 p.m.) (Question ID: 4841)

  • Answers:
  • The standard enthalpy of formation for an element in its state is zero.

    Answered by Swastika Chandan (Apr 12, 2017 5:43 p.m.)
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What are the  7 types of unit cells? 

 

Posted by Mahendra bagul (Apr 11, 2017 4:57 p.m.) (Question ID: 4834)

Electrochemistry is the study of production of electricity from

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<input id="option_198136" name="option" ng-click="selectedOption(practiceData[counter].id, option.id)" ng-disabled="showResult" type="radio"/><label dynamic="option.option" for="option_198136">nuclear energy and the use of heat energy to bring about non-spontaneous chemical transformations</label>

<input id="option_198133" name="option" ng-click="selectedOption(practiceData[counter].id, option.id)" ng-disabled="showResult" type="radio"/><label dynamic="option.option" for="option_198133">energy released during spontaneous chemical reactions and the use of electrical energy to bring about non-spontaneous chemical transformations</label>

<input id="option_198135" name="option" ng-click="selectedOption(practiceData[counter].id, option.id)" ng-disabled="showResult" type="radio"/><label dynamic="option.option" for="option_198135">energy released during spontaneous chemical reactions and the use of heat energy to bring about non-spontaneous chemical transformations</label>

<input id="option_198134" name="option" ng-click="selectedOption(practiceData[counter].id, option.id)" ng-disabled="showResult" type="radio"/><label dynamic="option.option" for="option_198134">nuclear energy and the use of electrical energy to bring about non-spontaneous chemical transformations</label>

Posted by ashish jaiswal (Apr 10, 2017 10:32 p.m.) (Question ID: 4821)

The unit cell cube length for LiCl is 5.14angstrom . Assuming anion-anion contact, calculate the ionic radius for chloride ion.

Posted by Devansh Agarwal (Apr 10, 2017 7:53 p.m.) (Question ID: 4817)

Why people suffer from anoxia at high altitudes 

Posted by Abhishek Verma (Apr 10, 2017 10:04 a.m.) (Question ID: 4808)

  • Anoxia is a condition characterized by an absence of oxygen supply to an organ or a tissue.Anoxia results from a decrease in the amount of hemoglobin or RBCs in the blood, which reduces the ability to get oxygen to the tissues 

    Posted by Ayush Saini (Apr 10, 2017 10:58 a.m.)
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How more the rate constant & more will rate of reaction.

Posted by Vaalee Patil (Apr 09, 2017 6:30 p.m.) (Question ID: 4797)

1)How to calculate valency?  2)How to identify the whether it is a covalent or ionic compound ? 3)Is there any shortcut for to tell hybridisation? 4)How to calculate the l0ne pairs and bond pairs ?

Posted by doreamon superman (Apr 07, 2017 7:40 p.m.) (Question ID: 4768)

As the number of holes are equal to number of free electrons...

Plzz send me answers 

Posted by Yash Sharma (Apr 05, 2017 6:04 p.m.) (Question ID: 4728)

Why holes are majority carrier in p-type semiconductors 

Posted by Yash Sharma (Apr 05, 2017 6:02 p.m.) (Question ID: 4727)

  • Answers:
  • When intrinsic semiconductors like Si and Ge are doped with group-13 elements like B,Al or Ga which contains only three valence electrons, then the place where the fourth valence electron is missing is called electron hole.An electron from a neighbouring atom can come and fill the electron hole,but in doing so it would leave an electron hole at its majority position.

    Since, the number of holes are more than the number of electrons,therefore they are called as p-tyoe semiconductors and holes are the majority carriers.

     

    Answered by Shweta Gulati (Apr 07, 2017 12:11 p.m.)
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Which type of solid is libr , brass , (nh4)3po4 , 

Posted by Rohan Choudhary (Apr 01, 2017 10:03 a.m.) (Question ID: 4644)

  • Answers:
  • Solution : LiBr is Ionic, Brass is metallic, 

    (NH4)3PO4  is ionic.

    Answered by Payal Singh (Apr 01, 2017 10:51 a.m.)
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is p4h10 molecular solid

Posted by Rohan Choudhary (Apr 01, 2017 10 a.m.) (Question ID: 4643)

  • Answers:
  • Ans. Yes it is molecular 

    Answered by Payal Singh (Apr 01, 2017 10:46 a.m.)
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Why are secondary amines more basic than tertiary amines? 

Posted by Alish Mech (Mar 27, 2017 9:05 a.m.) (Question ID: 4544)

  • Answers:
  • Ans. A basic substance is capable of donating a lone pair towards forming a coordinate covalent bond. A secondary amine can donate its lone pair more easily, as the extra inductive effect stabilises the charge on the nitrogen atom.

    Answered by Naveen Sharma (Mar 27, 2017 10:26 a.m.)
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What is the formula of the compound of sulphur which is obtained when conc. HNO3 oxidises S8?

Posted by samantha d'souza (Mar 25, 2017 3:39 p.m.) (Question ID: 4502)

  • Answers:
  • Ans. S8+ 48HNO3 {tex}\to {/tex}8H2SO4 + 48NO2 + 16H2O

    Answered by Naveen Sharma (Mar 25, 2017 4:32 p.m.)
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What is the difference between molecular and ionic solid

Posted by Bhavna Rawal (Mar 24, 2017 11:19 p.m.) (Question ID: 4493)

  • Answers:
  • Ans.

    • Molecular compounds are pure substances formed when atoms are linked together by sharing of electrons while ionic compounds are formed due to the transfer of electrons.
    • Molecular compounds are made due to covalent bonding while ionic compounds are made due to ionic bonding.
    • Molecular compounds are formed between two non-metals while ionic compounds are formed between metals and non-metals.
    • Molecular compounds are poor electrical conductors while ionic compounds are good conductors.
    • Molecular compounds can be in any physical state ‘“ solid, liquid, or gas. Ionic compounds are always solid and crystalline in appearance.
    Answered by Naveen Sharma (Mar 25, 2017 6:40 a.m.)
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Why thermosetting polymers can not be reused ?

Posted by bhavna rathore (Mar 24, 2017 10:50 p.m.) (Question ID: 4487)

  • Answers:
  • Ans. Because it is a stable cross linked polymer which attain a particular shape by heat and pressure. Chemical bonds formed are very strong. This is the reason why thermosetting plastics melt only the first time and become firm after that.

    Answered by Naveen Sharma (Mar 25, 2017 6:50 a.m.)
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Actinides show irregularity in their electronic configuration?

Posted by Bhavna Rawal (Mar 24, 2017 10:37 p.m.) (Question ID: 4486)

  • Answers:
  • Ans. This happens because the energy difference between 5f, 6d and 7s subshell of the actinides is very small and hence electrons can be accommodated in any of them.

    Answered by Naveen Sharma (Mar 25, 2017 4:44 p.m.)
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Difference between nucleotide and nucleoside 

 

Posted by Bhavna Rawal (Mar 24, 2017 10:36 p.m.) (Question ID: 4485)

  • Answers:
  • Ans.

    Nucleoside Nucleotides
    1. A nucleoside consists of a nitrogenous base covalently attached to a sugar (ribose or deoxyribose) but without the phosphate group. 1. A nucleotide consists of a nitrogenous base, a sugar (ribose or deoxyribose) and one to three phosphate groups.
    2. Several nucleoside analogues are used as antiviral or anticancer agents. 2. Malfunctioning nucleotides are one of the main causes of all cancers known of today.
    3. Nucleoside = Sugar + Base 3. Nucleotide = Sugar + Base + Phosphate
    4.Examples of nucleosides include cytidine, uridine, adenosine, guanosine, thymidine and inosine. 4. Nucleotides follow the same names as nucleosides, but with the indication of phosphate groups. For example, 5'-uridine monophosphate.

     

    Answered by Naveen Sharma (Mar 25, 2017 7:16 a.m.)
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What is lanthanides contraction? What are its causes and consequences?

 

Posted by Bhavna Rawal (Mar 24, 2017 7:17 p.m.) (Question ID: 4482)

  • Answers:
  • Ans. Lanthanide Contraction: The steady decrease in the size of lanthanide ions (M3+) with the increase in atomic no. is called lanthanide contraction.

    Causes: As we move down the group from left to right in a lanthanide series, the atomic no. increases and for every proton in the nucleus the extra electron goes to 4f orbital. The 4f orbital is too diffused to shield the nucleus effectively, thus there is a gradual increase in the effective nuclear charge experienced by the outer electrons. Consequently , the attraction of the nucleus for the electrons in the outermost shell increases with the increase of atomic number, thus size decreases.

    Consequence of Lanthanide Contraction:

    • Separation of Lanthanides: Due to the similar sizes of the lanthanides, it is difficult to separate them but due to lanthanide contraction their properties slightly vary (such as ability to form complexes). The variation in the properties is utilized to separate them.
    • Basic Strength of Hydroxide: Due to the lanthanide contraction, size of M3+ions decreases and there is increase in covalent character in M–OH and hence basic character decreases.
    • Similarity of second and third transition series:The atomic radii of second row transition elements are almost similar to those of the third row transition elements because the increase in size on moving down the group from second to third transition elements is cancelled by the decrease in size due to the lanthanide contraction.
    Answered by Naveen Sharma (Mar 25, 2017 7:21 a.m.)
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What is high enthalpy of atomisation in D-block?

Posted by Bhavna Rawal (Mar 24, 2017 7:16 p.m.) (Question ID: 4481)

  • Answers:
  • Ans. Enthalpy of atomisation is the change in enthalpy when one mole of bonds are completely broken to obtain atoms in the gas phase.

    Transition elements or D-Block elements have high effective nuclear charge and a large number of valence electrons. Therefore, they form very strong metallic bonds. As a result, the enthalpy of atomization of transition metals is high.

    Answered by Naveen Sharma (Mar 25, 2017 10:28 a.m.)
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Q1) Difference between ionic and atomic          radii?

Q2) what is ionization energy?

Posted by Bhavna Rawal (Mar 24, 2017 7:15 p.m.) (Question ID: 4480)

  • Answers:
  • Ans.

    1. Ionic radius is the distance between the nucleus and the valence shell of a stable ionic species whereas, atomic radius is the distance between the nucleus and the valence shell of an element in its stable ground state.
    2. The ionization energy (IE) is qualitatively defined as the amount of energy required to remove the most loosely bound electron, the valence electron, of an isolated gaseous atom to form a cation.
    Answered by Naveen Sharma (Mar 25, 2017 10:30 a.m.)
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